I have tried getting past the bug 7 or 8 times since december. Restarted the game plenty.
Or did you mean I should start a brand new game?
Plenty people have had problems with bugs in that quest. Especially if Dorian is in their party (he isn't in mine though).
Lots of people complained about that bug on the DA Facebook page. One of the posts there had almost 100 replies. EA\BIoware deletes stuff like that fairly fast. I have seen posts about the issue lots of times but it gets removed.
Lovely customer treatment there.
I thought the last patch addressed the Dorian bug 0o (I know you said your issue isn't caused by Dorian, since he isn't in the party, I'm only referring to how you listed the Dorian bug as something people have complained about and Bioware just deleted those comments.)
As for your bug - that seems really odd. Especially since I vaguely remember the cutscene doesn't actually require you to clear out all the enemies in the area. Want to say the last time I played through that scene the cutscene started as soon as I killed the Harlequin. Don't know how helpful this advice will be, but I know with a bug I encountered later on in the game where I "defeated" an enemy but the script that was supposed to run after I defeated them didn't fire; I was able to solve the issue by running back to where the last cutscene played. Judging by what you said about running everywhere on the map, however, I imagine you tried this?
As for the issue regarding court approval - you have a chance to get a LOT of points right after this scene to make up for any you might have missed while searching the grounds. I remember I was convinced I'd fail the mission because my score was so low my first time through. After something you can do after this scene, I wound up with 100 court approval though.